Automatic merge from submit-queue

ScheduledJob kubectl

@erictune the last part (kubectl) of the ScheduledJob, as usual builds on top of previous PRs, so only last 2 commits matter (the kubectl one and storage leftovers).

```release-note
* Introducing ScheduledJobs as described in [the proposal](https://github.com/kubernetes/kubernetes/blob/master/docs/proposals/scheduledjob.md) as part of `batch/v2alpha1` version (experimental feature).
```
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